1. Field of the Invention
The present invention relates to an image forming apparatus provided with an opening cover, particularly with a vertical conveyance cover which is opened and closed at the time of a jam processing.
2. Description of the Related Art
In an image forming apparatus such a printer or a copier for forming an image on a sheet by an electrophotographic method, an electrostatic latent image formed on an image bearing member such as a photoconductive drum is developed into a toner image and this toner image is transferred to a sheet fed at a suitable timing by a pair of registration rollers. The sheet having the toner image transferred thereto is conveyed to a fixing unit and is discharged onto a discharge tray outside the apparatus after having the toner image fixed by heat and pressure in the fixing unit. In this way, a series of image forming operations are completed.
There is known an image forming apparatus provided with a vertical conveyance cover which is openable and closable and constitutes a part of a sheet conveyance path so that a jammed sheet can be easily removed in the case of a jam in the sheet conveyance path during an image forming operation.
A known image forming apparatus of this type is such that a vertical conveyance cover is made up of an outer cover and an inner cover, which are independently opened and closed, and the position of the inner cover is determined by being pushed by the outer cover during a closing operation (see, for example, Japanese Unexamined Patent Publications Nos. 2005-138967 and 2004-123393).
In such an image forming apparatus, the outer and inner covers of the vertical conveyance cover are locked onto an apparatus main body by means of hooks respectively provided on these outer and inner covers. In this case, there is also proposed an image forming apparatus provided with a link mechanism for operating a link of an inner cover as a hook of an outer cover is operated (see, for example, Japanese Unexamined Patent Publications No. 2005-055862).
However, if the outer and inner covers of the vertical conveyance cover are locked onto the apparatus main body by means of the hooks respectively provided on these outer and inner covers, the number of parts increases. Further, since the opening/closing operability of the outer and inner covers is deteriorated, there has been a problem of reducing the operability of a jam processing.